Maternal cardiovascular adaptations appear to be essential in order to supply extra circulation to both the developing fetus and maternal system during a successful pregnancy. Since inadequate cardiovascular adjustments may produce abortions or maternal morbidity, the characterization of maternal cardiovascular changes during pregnancy and the elaboration of the underlying mechanism for these changes are essential to the understanding of how the heart enlarges during pregnancy and what significance this enlargement might have. To provide needed information regarding this time course and extent of maternal cardiac enlargement and the hormonal and hemodynamic changes which may be responsible for these changes, the guinea pig was used as an animal model to characterize the maternal cardiac, hemodynamic and hormonal changes during early, mid and late pregnancy.

Luo Guo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 97-109). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.2 / Chapter 1.2 --- Basics --- p.3 / Chapter 1.2.1 --- Anatomy of Human Heart --- p.3 / Chapter 1.2.2 --- The Philosophy of MRI --- p.5 / Chapter 1.2.3 --- MRI in Practice --- p.7 / Chapter 1.3 --- Cardiac MR Images Analysis --- p.7 / Chapter 1.3.1 --- Heart Boundary Segmentation --- p.7 / Chapter 1.3.2 --- Motion Reconstruction --- p.13 / Chapter 1.4 --- Summary and Thesis Overview --- p.17 / Chapter 2 --- Tracking Tags in SPAMM Images --- p.21 / Chapter 2.1 --- Introduction --- p.21 / Chapter 2.2 --- The Snake Model --- p.28 / Chapter 2.3 --- The Improved Snake Model: Tracking Tags Using Snakes --- p.30 / Chapter 2.3.1 --- Imaging Protocol --- p.30 / Chapter 2.3.2 --- Model Formulation --- p.31 / Chapter 2.3.3 --- Numerical Solution --- p.39 / Chapter 2.4 --- Experimental Results --- p.44 / Chapter 3 --- B-Spline Based LV Motion Reconstruction --- p.52 / Chapter 3.1 --- Introduction --- p.52 / Chapter 3.2 --- LV Shape: Generalized Deformable Ellipsoid --- p.56 / Chapter 3.3 --- The New Geometric Model: Generalized Prolate Spheroid --- p.58 / Chapter 3.3.1 --- Generalized Prolate Spheroid --- p.58 / Chapter 3.3.2 --- Initial Geometric Fitting --- p.59 / Chapter 3.4 --- Fast Motion Reconstruction: The Enhanced Hi- erarchical Motion Decomposition --- p.65 / Chapter 3.4.1 --- Hierarchical Motion Decomposition --- p.65 / Chapter 3.4.2 --- Motion Reconstruction --- p.68 / Chapter 3.4.3 --- Implementation --- p.76 / Chapter 3.4.4 --- Time Smoothing --- p.77 / Chapter 3.5 --- Experimental Results --- p.79 / Chapter 3.5.1 --- Geometric Fitting --- p.79 / Chapter 3.5.2 --- Motion Reconstruction --- p.79 / Chapter 4 --- Conclusion --- p.93 / Bibliography --- p.109

The hematological and rheological characteristics of blood from a number of vertebrates was compared to assess possible species differences in blood viscosity that may influence cardiovascular oxygen transport. Nucleated red blood cells (RBCs) were more viscous (measured by cone-plate viscometry) in comparison with enucleate (mammalian) RBCs at hematocrits greater than 40% when measured at equivalent temperatures. The lower viscosity of enucleate RBCs is attributed to an enhanced deformability of enucleate cells in comparison to nucleated cells.

published_or_final_version / abstract / toc / Medicine / Master / Doctor of Medicine

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.

Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1999. / Appendum consists of last two leaves. Copies of author's previously published articles inserted. Bibliography: leaves 241-283.

This investigation was concerned with measuring aspects of cardiac function in conscious control, diabetic, hypertensive control, and hypertensive diabetic rats. Preliminary studies were conducted to determine catheter suitability and acute responses to atropine and angiotensin II in conscious animals. The catheter-manometer was tested using a square wave impact and was shown to accurately reproduce a left ventricular pressure pulse. Intravenous atropine caused both heart rate and left ventricular +dP/dt to rise. Intravenously administered angiotensin II caused systolic blood pressure to increase dramatically. In this case heart rate fell and +dP/dt was elevated. Hypertension was induced with deoxycorticosterone acetate (DOCA) and saline drinking water. Rats were first made diabetic with streptozotocin (60 mg/kg; i.v.). One week following this, subcutaneous DOCA (25 mg/kg) was administered twice weekly and all animals received saline drinking water. Following 2 and 5 weeks of DOCA treatment rats were catheterized and resting cardiovascular function was measured. DOCA treatment caused increased systolic and diastolic blood pressures to occur in control and diabetic rats at 2 and 5 weeks. Bradycardia was also observed in DOCA-diabetic and DOCA-control rats at 2 and 5 weeks of treatment. Two and 5 week hypertensive diabetic and control rats exhibited elevated -dP/dt and +dP/dt. The rate of contraction was shown to be proportional to the magnitude of systolic blood pressure in all treatment groups. It is concluded that diabetic rats and control rats did not differ in their response to hypertension after 5 weeks of DOCA treatment. / Medicine, Faculty of / Anesthesiology, Pharmacology and Therapeutics, Department of / Graduate

The effects of steady-state, aerobic swimming exercise upon blood volume and flow distribution in the rainbow trout {Salmo gairdneri) were examined. Isotopic Rubidium-86, and radiolabelled microspheres were injected into trout forced to swim against a current at 80% of their critical velocity (U[sub=crit]) in a Brett-type water tunnel respirometer. The results gathered from experiments using these radioactive tracers within the circulatory system of the trout indicated that blood flow during exercise was redistributed to favour working muscles, at the expense of diminished blood flow to those organs and tissues in the systemic circulation which could tolerate periods of transient hypoxia. Active hyperaemia in the skeletal muscle and vasoconstriction of the coeliacomesenteric artery, via adrenergic receptor mechanisms are proposed as the main sites of the control for blood volume and flow redistribution in the systemic circulation in trout during exercise. The gills of these fish must be able to maintain adequate gas transfer in order to keep pace with the increased metabolic demands of the working muscles during exercise. An isolated, saline-perfused trout head preparation and a spontaneously ventilating, blood-perfused whole trout preparation were developed in order to study how increases in the pulsatility of input and increases in the cardiac output through these gills; cardiovascular alterations known to occur during exercise in vivo in these fish, affect fluid flow distribution through, and within the branchial vasculature, and gas exchange across the gills. Data from these preparations indicated that pulsatility of flow increased venolymphatic fluid drainage from within gill tissues, as well increasing the fluid flux/reflux across the branchial microvasculature. However, these changes in fluid distribution associated with increased pulse pressure did not significantly change the rate of gas transfer across the gills. Although gill vascular resistances to flow were very sensitive to alterations in pulse pressure and flow rate, only perfusion flow rate through the gills could cause significant changes in the rate of mass transfer of gases across the gills. The gills of trout therefore were found to be perfusion and not diffusion limited for gas transfer, under conditions which simulated those found at rest and during exercise, in vivo. It also was shown that, given oxygen uptake and cardiac output data from the literature, combined with those for blood flow redistribution during exercise from the present study, the working muscles, which were operational during steady-state, aerobic swimming exercise in rainbow trout, could account for nearly all the measured increase in the total oxygen uptake at this level of exercise. The circulatory system of the rainbow trout, both branchial and systemic, was shown to be quite efficient in its ability to take up and distribute oxygen to the tissues during prolonged, aerobic swimming exercise. The numerous cardiorespiratory adjustments noted during exercise account for this animal's ability to maintain swimming activity in the face of increased oxygen demands put upon the circulation by enforced activity. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

The events of cardiac surgery combined with moderate hypothermia hemodilution perfusion and postoperative respiratory care provide the stimuli for the alteration of K+ levels in red blood cells, plasma, and urine. The purpose of this study was to measure the deviations from normal potassium ion concentrations in an attempt to understand the physiological processes involved.